Conventionally, a semiconductor memory is designed so that each of the memory cells includes a storage element, a select element, and an information extracting line.
In recent years, shift-register memories have been suggested so as to realize larger memory capacities. This suggestion is based on the concept that only storage elements are arranged at high density, and the system is designed for transferring stored information to the location of a sensor formed in a predetermined site or an interconnect. Accordingly, there is a possibility that the memory capacities can be dramatically increased. In view of the purposes of development of the shift-register memories, placing a control electrode in each bit (each digit) is not desirable, and a shift operation for a desired digit number needs to be performed by adding some function to the entire bit string.
However, accurate shifting of information in all digits is not easy.